Welding unit with improved transformer tap and switch construction

ABSTRACT

A core type transformer for an AC welder has a primary and a secondary winding composed of a plurality of wire turns. In manufacturing the secondary winding, individual wire turns are preselected and pulled away from the remaining body of wire turns so as to form a wire loop. The wire loops function as winding taps and each of the wire loops is connnected within the welder enclosure to one of a plurality of positions selectively engageable by a switch assembly. The switch assembly includes a rotatable shaft which is operatively connected to a switch body on a first end and extends through the enclosure on a second end. An indicator means in the form of a pointer is mounted to the second end of the shaft. The enclosure has at least two scales concentrically arranged on it, each extending over an arc of less than 180*. Rotation of the switch assembly and the pointer in particular, in either direction over 180* automatically changes scales.

[ Aug. 20, 1974 383,262 10/1923 Germany............................ 197,713 10/1962 Sweden...... 739,376 10/1955 WELDING UNIT WITH IMPROVED TRANSFORMER TAP AND SWITCH CONSTRUCTION [75] Inventors: Richard B. Brundage, St. Louis;

Great Britain Walter P. Just, Jr Manch t Primary Examiner-Thomas J. Kozma both of Mo. Attorney, Agent, or FirmPolster and Polster [73] Assignee: Emerson Electric Co.,

St. Louis, Mo.

ABSTRACT 22 Filed: June 6,1973

.21 App1.No.:367,486

A core type transformer for an AC welder has a primmmmm m w n U u pollws miWd d aans w mm mm dww w ee fi w mmm P dwu h m w mb r m ywmm nedooo .m o o t be m m o .l r w m .m M mune t t-l r. an e a mem h 0 h w n f w m eam im n S ut Ce a m fi m dd awmfi a ma ww wms owm mo.maftt CQJU D UUl wzll 13 9 WQJIEBE OAU70-7111 25H5111 A C EM m T 13 51 1 "3 W mM 05 "3A 212E 944M311 0 n 93 n n/ W2 "O 3 u "0 3 NW w o m mm n W89 a m d3 s a U I F selectively engageable by a switch assembly. The

[56] References Cited UNITED STATES PATENTS switch assembly includes a rotatable shaft which is operatively connected to a switch body on a first end and extends through the enclosure on a second end. An indicator means in the form of a pointer is mounted to ...200/llE e second end of the shaft. The enclosure has at least two scales concentrically arranged on it, each extending over an arc of less than Rotation of the pointer in particular, in either automatically changes scales.

Arnejo Royer et a1. 966 Cannon.......... Meadows et a1...

Ludlum et al.

FOREIGN PATENTS OR APPLICATIONS 18 Claims, 9 Drawing Figures 1,239,008 4/1967 Germany............................

PAIENTEDAUBZOW names arm 1 or 4 1 WELDING UNIT wrrn IMPROVED TRANSFORMER TAP AND SWITCH CONSTRUCTION BACKGROUND OF THE INVENTION and a secondary part, likewise composed of a plurality of secondary wire turns. The transformer secondary winding is tapped in order to provide a variety of ampere ratings for the welder. Conventionally, the taps are made during winding of the secondary coil. A wire lead is attached to the transformer by some convenient method. The lead wire conventionally is a copper strap which is brought out of the transformer coil and connected to a switch remotely located with respect to the transformer. Because of the connection technique used 1 in the secondary, and the remote location of the switch, the connection wire between the tap and the switch are relatively long. The switch also conventionally is placed some distance from the transformer in order to provide sufficient space to make the necessary connections during the welder manufacturing process. In addition to requiring a relatively large enclosure, this combination of factors greatly increases manufacturing costs for the unit.

Our invention utilizes a novel construction which eliminates the lead wire connections between the transformer taps and the switch by in fact utilizing loops of the transformer wire turns for connecting the transformer directly to the switch. The switch is aligned vertically with the transformer core and is positioned near it. Consequently, both overall enclosure size and the total welder cost are reduced substantially. The switchtransformer arrangement also permits multiple scale.

presentation of welding heats or ampere settings on the welder enclosure.

One of the objects of this invention is to provide a low cost AC welder.

Another object of this invention is to provide a welder unit having a transformer with a tapped secondary winding in which loops of wire formed from turns of the secondary winding are used for each tap, those wire loops being directly connected to a switch assembly for the welder unit.

Still another object of this invention is to provide a welder having a novel switch arrangement which permits scales for the ampere rating of the welder to appear concentrically on the welder enclosure.

Yet another object of this invention is to provide a switch and rotatable shaft for operating the switch, which combination permits concentric movement of the shaft.

Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.

SUMMARY OF THE INVENTION In accordance with this invention, generally stated, an AC welder has a transformer with a primary winding and a secondary winding disposed about a core of magnetic material. Certain ones of the wire turn plurality comprising the secondary winding are looped in their construction and these wire loops define taps for the transformer after the wound coil is placed on the transformer core. The wire loops are connected directly to a switch. The switch is designed to permit concentric presentation of at least two scales on the welder enclosure and concentric operation of the shaft operatively connected to the switch.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 5 is a sectional view taken along the line 55 p of FIG. 4;

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 4;

FIG. 7 is a sectional view taken along the line 7-7 of FIG. 4;

FIG. 8 is a view of a connection diagram for the welder illustrated in FIG. 1; and

FIG. 9 is a sectional view taken along the line 99 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, reference numeral 1 indicates the preferredembodiment for the AC welder of this invention. Welder 1 includes an enclosure 2 having afirst pair of oppositely opposed side walls 3 and 4, a second pair of oppositely opposed side walls 5 and 6, a bottom wall 7, a top wall 8 and a hip wall which joins the side wall 5 to the top wall 8. The enclosure 2 conventionally is constructed from sheet metal and individual components of the enclosure 2 may be interconnected by conventional sheet metal screws. Various ones Of the walls comprising the enclosure 2 may be integrally formed with one another, if desired.

Side walls 3 and 4 are identical and preferably have a plurality of louvers 9 in them. which vent a chamber 10, defined by enclosure 2, to the surrounding environ ment.

Side wall 5 generally is rectangular in plan, and has a pair of openings 11 through it, which provide egress for a pair of welding leads l2 and 94 respectively. The leads l2 and 94 are conventional and may comprise any of a variety of common electrical cables capable of handling the current loads of the Welder 1. The lead 12 terminates in an electrode holder 96, while the lead 94 terminates in a ground clamp 97.

Side wall 6 also has an opening in it, not shown, which permits egress from the chamber 10 for a line cord 13. Line cord 13 also is conventional and is terminated on one end by a conventional plug 14. A second end of line cord 13 is electrically connected to a primary winding side 98 of a transformer 16 through a switch 17, as is best seen in FIG. 8. Primary winding side 98 includes a primary winding 15. For best results, the line cord 13 should be as short as possible.

Top wall 8, bottom wall 7 and hip wall 95 also are generally rectangular in plan. Hip wall 95 has an opening 93 in it through which an actuator portion of the switch 17 extends. Top wall 8 has a carrying handle 92 attached to it. Other features of top wall 8 are described hereinafter.

Transformer 16 includes a core 18 which has the primary winding and a secondary winding 19 disposed about it. The core 18 is conventional in that it comprises a plurality of laminations constructed from magnetic material. In the embodiment of FIG. 1, the laminations are L-shaped and two sections of the lamination are joined to form the rectangular core 18 illustrated.

Primary winding 15 is conventional and it includes a plurality of wire turns which are wound by suitable means into the coils illustrated in FIG. 3, about a leg 106 of the core 18. Winding may be accomplished by a variety of conventional techniques, well known to those skilled in the art.

Secondary winding 19 also includes a plurality of wire turns. However, winding 19, as best seen in FIG. 8, comprises a number of coil sets which in total make up a secondary side 99 of the transformer 16. A closely coupled portion 105 of the secondary winding 19 is mounted on the same leg 106 of the core 18 as the primary winding 15. A loosely coupled portion 109 of the secondary winding 19 is mounted ona leg 107 of the core 18. A choke coil set 108 is wound around the perimeter of the core 18. The function and purpose of coil 108 is known in the art and a more detailed description of the coil 108 is given in the US. Pat. No. to Royer et 211., 3,237,090 issued Feb. 22, 1966.

Preselected ones of the individual wire turns of the various coil sets comprising the second side 99 are looped, during the coil winding process, to form a plurality of wire loops 20. Wire loops 20 are actual turns of the various coil sets and may be formed by a number of methods during the coils winding process. For example, the wire loops 20 may be formed by grasping the wire strand used to form the winding 19 at preselected intervals as the coil is being wound, drawing sufficient wire outwardly from the wire coil main body, and resuming normal winding operations, thereby forming the wire loop 20. A fastener 21 may be attached to the wire loop 20 as an aid in maintaining loop 20 position during the remaining manufacturing steps. While loops of any length may be drawn in the manner described, it is economical if the loops 20 are as short as possible in order to effectuate greatest cost savings. in commercial embodiments of this invention, the wire loops generally are formed so that their length is approximately 6 V2 inches. The preferred embodiment, as illustrated in FIG. 8, has eight wire loops .20 formed in the secondary side 99. These loops, together with start and finish wires of the various coils define the winding taps for the transformer 16.

Use of the wire loops in the choke coil 108 is known in the art, where they are attached to some type of additional lead material, for example copper strips, and connected to a remote switch structure. However, the use of wire loops 20 in the loosely coupled portion 109 of the secondary winding 19 heretofore has been assumed to be unsuitable by those skilled in the art. Unsuitability was predicated on the fact that relatively large wire sizes are used in the portion 109. The larger wire sizes are difficult to handle under the demands of a production line. Thus, for example, indiscriminate loop formation in the portion 109 often results in bunching of the wire turns. Bunching is not desirable because crossed wires in an electrical apparatus results in an area of potential insulation breakdown and subsequent apparatus failure. These difficulties are largely eliminated if the portion 109 is layer wound over the leg 107 of the core 18, as illustrated in FIG. 9. The loops 20 are made along a top layer of the portion 109. Thereafter, the loops 20 of both the coil 108 and the portion 109 are connected directly to a selecting switch assembly 31, later described in detail. It is helpful, in the operation of the transformer 16, if the primary winding 15 and secondary winding 19 are spaced from the core. Spacer-retainer blocks 111, which may be in the form of plastic wedges, are used to hold the windings in place, and to ensure proper spacing from the core 18.

The core 18 is attached to a bracket 22 along a first end thereof and to a bracket 23 along a second end thereof. Attachment may be made by any convenient method. Either arc welding or epoxy adhesive work well.

The bracket 23 is a continuous, inverted V-shaped bracket attached to the core 18 along the apex of the V, which includes a plateau portion (not shown) for supporting the core 18. The legs of the V have outwardly extending mounting pads 24 for securing the bracket 23 to the bottom wall 7 of enclosure 2. Other configurations for the bracket 23 work well. For example, the bracket 23 may comprise individual beam parts attached to the core at one end and to the bottom wall 7 on their other end. These other bracket 23 embodiments are compatible with the broader aspects of this invention.

Bracket 22 includes an bshaped part 25, an outwardly extending part 26, and a pad part 27. Part 25 of bracket 22 includes a short leg 28 and a long leg 29. The short leg 28 of part 25 has a body 30 of switch assembly 31 mounted to it by any convenient method. Conventional threaded fasteners work well. The long leg 29 of part 25 has the core 18 attached to it, along an end opposite the juncture of the legs 29 and 28. It

may be observed, in FIG. 3, that use of the bracket 22 permits the body 30 of switch 31 to be located in close proximity to the core 18. In addition, the use of the brackets 22 and 23 positions the core 18 above the bottom wall 7 of enclosure 2, permitting air to circulate about the core 18 and windings 15 and 19. A fan 32 may be provided within the enclosure 2 as an aid in air circulation. When utilized, it is convenient to connect the fan 32 across the switch 17, as is best observed in H6. 8.

The body 30 of switch assembly 31 is circular in plan and includes an underside 42 and an upper surface 35. The surface 35 defines a rim 33 and a raised part 34 inboard of the rim 33. The surface 35 has a connector 36 formed in it, which is used to attach the body 30 to the leg 28 of the bracket 22. Surface 35 also has a centrally located hub 37 extending upwardly from it. The hub 37 has an opening 38 through it. The opening 38 has a first diameter 39 and a second diameter 40 formed along it.

The diameter 39 and are important. The two diameters give a shaft an added degree of flexibility in that they permit concentric movement of the shaft 50. The flexibility provided means that some misalignment between the switch assembly 31 and an opening 89 in top wall 8 of the enclosure 2 can be tolerated in the manufacturing process. Any misalignment is compensated by .the flexibility provided by the diameters 39 and 40 which allow flexible shaft 50 positioning. The hub 37 extends through the body 30 and projects outwardly from the underside 42. The body 30 has a lip 100 formed integrally with the rim 33 and extending radially outwardly from it. The lip 100 defines a mounting area. 44 and an electrical conductor 43 is attached to the body 30 along the area 44 by a pin 45. The pin 45, a number of which are used in the switch assembly 31, is .a conventional fastener which is bent or coined over to attach various components of the switch assembly 31 to one another. Other fasteners can be used, if desired.

The conductor 43 has a first end 46 and a second end '47. The ends 46 and 47 have openings 48 and 49 respectively in them. The opening 48 is utilized to attach the lead 12 to the switch assembly 31. Connection may be made by conventional threaded fasteners. The opening49 in the conductor 43 forms a channel 41 with the opening 38 of the hub 37, permitting passage of the shaft 50, as explained hereinafter. It may be observed, in FIG. 5, that the conductor 43 is manufactured to conform to the cross sectional configuration of the underside 42 of body 30. Conductor 43 preferably is a copper strip although other electrically and mechanically suitable materials may be used.

As indicated, shaft 50 extends through the channel 41 defined by the openings 38 and 49. Shaft 50 is a polygonal body having an end 51 and an end 52. The ends 51 and 52 each have threaded openings 53 and .54, re spectively, in them.

The end 52 of shaft 50 has a pointer 55 attached to it. Pointer 55 has a central hub 56 having an axial opening 91 through it, polygonal in cross-section, sized to receive the end 52 of the shaft 50 in a slip fit. The hub 56 extends outwardly from an underside 57 of the pointer 55. An upper side of the pointer 55 defines an indicator area 58. The pointer 55 has an opening 59 through it which interconnects with the opening 91 of the hub 56. A threaded fastener 60 is inserted through the opening 59 and .is used to attach the pointer 55 to the shaft '50 by entering the opening 53 in the end 52 of the shaft 50. The shaft 50 and pointer 55 are interlocked for simultaneous movement by the slip fit engagement of the polygonal body of the shaft 50 with the polygonal opening 91.

Indicator area 58 is divided into a part 61 and a part 62, of different radial lengths, along opposite sides of the opening 59. This configuration is important, as is described in detail hereinafter.

A retaining ring is attached to the shaft 50 along a groove 115 in the shaft 50. Ring 65 is conventional and a washer 64 is mountedover the end 51 of the shaft 50 after the ring 65 is in place. A spring 63 also is placed over the end 51 of the shaft 50. The washer 64 abuts the retaining ring 65 on one side, and the spring 63 on its other side in the assembled welder l. The spring 63 is designed to seat between the washer 64 and a seat 79 defined by an upper edge of the hub 37.

The end 51 of the shaft 50 extends through the hub 37 and the channel 41. A movable contact 66 has a body portion 67 having an opening 68 along a first end of it. A second end of contact 66 narrows and defines an end part 69. Contact 66 has a pair of dimples 70 formed on and extending outwardly from a top side 116 of the body portion 67. One of the dimples 70 is positioned near the opening 68 and the other near the end part 69. The contact 66 freely fits over the end 51 of the shaft 50. Contact 66 has a pair of edges 71 and 72 respectively which form a flange 102 along the underside of the contact 66. i

A guide 73 has an attaching area'74 intermediate of a clamping part and a clamping part 76. The area 74 has an opening 101 through it sized to pass the shaft 50 and to align with the openings 68, 49 and 38. As indicated, the shaft 50 extends through the openings 38, 49 and 68 and is attached along the attaching area 74 of guide 73 by a conventional threaded fastener 77. When secured to the shaft 50, the guide 73 is engaged along clamping parts 75 and 76 by the flange 102. This engagement clamps the movable contact 66 against the conductor 43 so that one of the dimples 70 abuts the conductor 43 while the dimple 70 near the end part 69 abuts one of a plurality of tap connectors 78. When so attached, the shaft '50 is spring loaded upwardly, as the spring 63 is positioned between the seat 79 of the hub 37 and the washer 64-retaining ring 65 combination. The retaining ring 65 transmits an upward force to the shaft 50. The movable contact 66 is loose fitting on the shaft 50 and the guide 73 ensures that it rotates with the shaft 50 during rotation of that shaft, described hereinafter.

The underside 42 of the body 30 has a plurality of spaced stops 80 arranged about the periphery of the rim 33. The stops 80 define a plurality of grooves 103 between adjacent stops. The tap connectors 78 are attached to the body 30 along the grooves 103. Connectors '78 are later described in detail. The stops 80 extend radially inwardly from the outer edge of the rim 33 and have a trapezoidal shape in plan. A radially inward part of the stops 80 has a decreased axial depth and this area of the stops 80 defines a detent 81 along each inboard portion of the stops 80.

The movable contact 66 is sized radially so that the end part 69 passes the stops 80 along the detent 81 portion thereof when the shaft 50 is depressed sufficiently to enable end part 69 disengagement with any particular groove 103.

As indicated above, the tap connectors 78 are attached to the body 30 along the grooves 103. Each tap connector 78, as seen in FIGS. 6 and 7, is L-shaped in side elevation, having a short leg 82 and a long leg 83. The leg 82 has an opening in it and one of the .pins 45 is inserted through the leg 82 and a corresponding opening in the body 30 to secure one to the other. The leg 82 is rectangular in plan and substantially covers the area of the groove 103.

The leg 83 of connector 78 extends outboardly upwardly of the surface 35 of the body 30. The tap connectors 78 have the wire loops 20 attached to them. As an aid in that attachment, the leg 83 may assume a variety of configurations. Two such possible configurations are shown in FIGS. 6 and 7.

Referring now to FIG. 6, the leg 83 has a tine 84 formed in it. A wire loop 20 is placed over the tine to effectuate electrical continuity between a portion of secondary winding 19 and one of the tap connectors 78. As will be recognized by those skilled in the art, the wire turns used for transformer construction are constructed from magnet wire. Magnet wire is a term applied to an electrical conductor, commonly of copper or aluminum, that has an insulation film or coating applied to it. To insure proper electrical contact, the insulation film must be removed. We find it convenient to remove the insulation from the loop 20, insert the loop over the tine 84, and solder the connector 78 to the loop 20.

FIG. 7 illustrates another method of electrical connection particularly useful where the wire sizes involved are large. In this situation, the wire loop is cut and the wire film insulation is removed. The now two ends of the loop 20 are attached to the connector 78 by wrapping additional turns of connecting wire 85 about the connector and loop ends. This combination is then dip soldered to ensure proper electrical operation. Other connection techniques are compatible with the broader aspects of this invention.

It thus may be observed, in FIG. 4, that the body 30 of switch assembly 31 has twelve positions arranged annularly about its perimeter. Each of the twelve positions, represented generally by the numeral 104 in FIG. 8, is electrically connected to a portion of the secondary side 99 of the transformer 16. Individual ones of these positions may be selected by manipulation of the movable contact 66. The contact 66 connects one of the positions 104 to the conductor 43, and consequently to the welding lead 12.

Referring now to FIG. 1 and 2, the top wall 8 of the enclosure 2 has a plate 86 attached to it. The plate 86 has a pair of scales 87 and 88 respectively inscribed or printed on it. The scales 87 and 88 are positioned in an annular array and are concentric, with respect to one another, about an opening 90 in the plate 86. The scales extend over an arc of less than 180.

Top wall 8 has the opening 89 in it, and the shaft 50 extends through the opening 89. The opening 90 aligns with the opening 89 and the shaft 50 extends through, those openings. As indicated above, the pointer 55 is attached to the end 52 of the shaft 50. When so attached, the part 61 of the indicator area 58 will align itself with one of the scales 87 and 88 while the part 62 of the indicator area 58 will align with the otherof the scales 87 and 88 when the switch assembly 31 is rotated through 360, as is best seen in FIG. 2. That is, the switch assembly 31 automatically changes scales as it is rotated one complete revolution. This arrangement is important because it simplifies output reading choice during operation of the welder 1. Rotation of the shaft 50 is facilitated by the diameters 39 and 40 discussed above. The pointer 55 will inscribe a circle when rotated, even if some misalignment occurs between the opening 89 and the switch assembly 31, because of the dual diameter provided along the opening 38.

As indicated, the electrode cable 12 is attached to switch assembly 31, while, as shown in FIG. 8, the ground cable 94 is electrically connected to the transformer 16 at a connection point 112.

Operation of the welder l is simplified with the construction disclosed herein. Twelve loading heats or ampere setting selections may be made with the single pointer 55. When the part 61 is pointed toward ampere scale 87, its end will align with one of the scale 87 positions. The engagement of the end part 69 of movable contact 66 with a corresponding groove 103 locks the shaft 50 in place and prevents accidental position changes. When the pointer 55 is rotated the part 62 of the pointer 55 aligns with one of the scale 88 positions. Again, the shaft 50 locks in place whenever the part 69 is engaged in the corresponding groove 103. The end part 69 locks between adjacent detents 81 because of the biasing provided by the spring 63. To change the ampere selection, the operator pushes down on the pointer 55 until the end part 69 disengages the groove 103, formed. by the detent 81, and releases the pointer after rotating it to a new position. Upon release, the switch assembly 31 will be back biased by the spring 63 and will lock into the newly selected position. An electrical circuit is made from the secondary winding 19, the wire loop 20, the tap connector 78, the movable contact 66, conductor 43, and the electrode cable 12.

Numerous variations, within the scope of the appended claims, will be apparent to those skilled in the art in light of the foregoing description and accompanying drawings. Thus, the silhouette of the enclosure 2 may be varied. Whilethe scales 87 and 88 were indicated as being placed on the plate 86, the scales may be inscribed directly on the enclosure. The number of positions in the switch assembly 31 may be varied. Although 12 positions are shown in the drawings, a variety of other combinations may be used. The shaft 50 need not extend through the enclosure 2, as described above. For example, the hub 56 may be made sufficiently long so that it meets the shaft 50 with the chamber 10. While a particular connection diagram is illustrated in FIG. 8 of the drawings, a variety of other electrical connection diagrams may be employed with the welder of this invention. These variations are merely illustrative.

Having thus described the invention, what is claimed and desired to secure by Letters Patent is:

l. A welding apparatus comprising:

an enclosure defining a chamber, said enclosure having an opening through it, said opening having at least a first scale and a second scale concentrically arranged about it, each of said scales extending over an arc of less than 180;

a transformer mounted in said chamber, said transformer including a winding composed of a plurality of wire turns arranged electrically to define a primary side and a secondary side for said transformer,the wire turns of said secondary side of said transformer being looped in their manufacture, said plurality of wire turns of said secondary side being arranged in layers about said core, said wire loops being formed from the outermost layer, with respect to said core, of said wire turns;

a switch mounted to said enclosure in close proxmity to said transformer, said switch having a plurality of positions, each of said plurality of positions having selective ones of said wire loops of said secondary transformer side being physically attached to it, said switch including a plurality of tap connectors mounted to it, individual ones of said tap connectors defining said switch positions, said wire loops being placed over said tap connectors; and

a shaft operatively connected to said switch, said shaft having a pointer attached to it, at least a part of said pointer being outboard of said enclosure, said pointer having a first indicator part and a second indicator part associatedwith it, one of said first and said second indicator parts being adapted to indicate a position onsaid first scale and the other of said first and said second indicator parts being adapted to indicate a position on said second scale as said pointer is rotated through 360.

2. The apparatus of claim 1 wherein said shaft is spring biased outwardly of said enclosure.

3. The apparatus of claim 2 wherein said switch includes a hub having an axial opening in it, said axial opening including a first axial length having a first diameter and a second axial length having a second diameter.

4. In a welding apparatus having an enclosure, a transformer mounted in said enclosure including a core of magnetic material and a winding composed of wire turns mounted on said core, said winding defining a primary side and a secondary side for said transformer, the improvement comprising a switch assembly, said switch assembly including a body part and a shaft, said shaft being rotatably mounted to said body part at a first end and having a pointer mounted on a second end of it, said switch body having a plurality of terminals, individual ones of said terminals having preselected individual ones of said wire turns physically attached to it, said enclosure having at least a first scale and a second scale concentrically arranged on it, each of said scales extending over an arc of less than 180, said pointer having a first indicator part and a second indicator part associated with it, one of said first and said second indicator parts adapted to indicate a position on said first scale and the other of said first and said second indicator parts adapted to indicate a position on said second scale sequentially as said shaft is rotated through 360.

5. The apparatus of claim 4 wherein said shaft is spring biased outwardly of said enclosure.

6. The improvement of claim 5 wherein said switch body is circular in plan and includes a centrally located hub having an axial opening therethrough, said shaft extending through said axial opening, said axial opening having a first axial length of a first diameter, and a second axial length of a second diameter, said hub receiving said shaft along the second end of said shaft,

said first and said second diameters permitting concentric movement of said shaft.

7. The improvement of claim 6 wherein said switch body has a plurality of grooves formed in it and a plurality of tap connectors mounted to said body along said grooves, said tap connectors defining said plurality of switch positions, said movable contact being selectively cngagable with individual ones of said tap con-' nectors.

8. The improvement of claim 7 wherein said tap connectors are L-shaped in side elevation and are mounted to said switch body along one leg of said L-shape and extending outboardly upwardly of said switch body along a second leg of said L-shape.

9. The improvement of claim 8 wherein each of said L-shaped tap connectors has a tine formed in said second leg.

10. The improvement of claim 9 wherein said secondary winding includes a first coil part disposed about said core, said coil part being formed by a plurality of wire turns wound in layers about said core, the outermost layer of said wire turns being formed in loops at preselected intervals along said layer, individual ones of said wire loops being electrically connected to said tap connectors along said tine of said second leg.

11. In a welding apparatus having an enclosure, a transformer mounted in said enclosure including a core of magnetic material and a winding composed of wire turns mounted on said core, said winding defining a pri- -mary side and a secondary side for said transformer,

the improvement comprising a switch assembly, said switch assembly including a body part and a shaft, said shaft having a first end and a second end, said shaft being rotatably mounted to said body part at its first end and having a pointer mounted along its second end, said switch body having a plurality of terminals, individual ones of said terminals having preselected ones of said wire turns electrically attached to it, said enclosure having at least a first scale and a second scale concentrically arranged on it, each of said scales extending over an arc of less than l80", said pointer having a first indicator part and a second indicator part associated with it, one of said first and said second indicator parts adapted to indicate a position on said first scale and the other of said first and said second indicator parts;

adapted to indicate a position on said second scale sequentially as said shaft is rotated through 360.

12. The improvement of claim 11 wherein said secondary side has said wire turns wound in layers, preselected ones of said wire turns of said secondary side being looped in their manufacture, said wire loops being formed from the outermost layer, with respect to said core, of said secondary side of said winding.

13. The improvement of claim 12 wherein said terminals comprise L-shaped connectors, one of the legs of said L-shape having a tine formed in it, the wire loops of said secondary side being placed over said tine to physically attach said secondary side to said switch assembly.

14. The improvement of claim 12 wherein said terminals comprise L-shaped connectors, said wire loops of said secondary side being soldered to one leg of said L- shape to physically attach said second winding to said switch assembly.

15. In a welding apparatus having an enclosure, said enclosure having at least one opening in it, a transformer mounted in said enclosure including a core of magnetic material and a winding formed from a plurality of wire turns mounted on said core, said winding defining a primary side and a secondary side for said transformer, the improvement comprising a switch assembly, said switch assembly including a body part and a shaft, said body part including a hub having an axial opening through it, said axial opening having a first axial length with a first diameter, and a second axial length with a second diameter, said shaft having a first end and a second end, said hub receiving said shaft along the first end of said shaft, the arrangement of said first and said second diameters permitting axial and radial movement of said shaft, said radial movement of said shaft permitting the second end of said shaft to be aligned with the opening in said enclosure and allow free rotation of said shaft, said shaft having a pointer mounted along the second end of it, said switch body having a plurality of terminals, individual ones of said terminals having preselected individual ones of the wire turns defining said secondary side of said transformer electrically connected to it.

16. The apparatus of claim 15 wherein said enclosure has at least a first scale and a second scale concentrispring biased outwardly of said enclosure.

18. The apparatus of claim 16 wherein said secondary side of said transformer includes at least a secondary winding coil having a plurality of turns arranged in layers about said core, the wire turns of said secondary coil being looped in their manufacture, said wire loops being formed from the outermost layer, with respect to said core, of said wire turns. 

1. A welding apparatus comprising: an enclosure defining a chamber, said enclosure having an opening through it, said opening having at least a first scale and a second scale concentrically arranged about it, each of said scales extending over an arc of less than 180*; a transformer mounted in said chamber, said transformer including a winding composed of a plurality of wire turns arranged electrically to define a primary side and a secondary side for said transformer, the wire turns of said secondary side of said transformer being looped in their manufacture, said plurality of wire turns of said secondary side being arranged in layers about said core, said wire loops being formed from the outermost layer, with respect to said core, of said wire turns; a switch mounted to said enclosure in close proxmity to said transformer, said switch having a plurality of positions, each of said plurality of positions having selective ones of said wire loops of said secondary transformer side being physically attached to it, said switch including a plurality of tap connectors mounted to it, individual ones of said tap connectors defining said switch positions, said wire loops being placed over said tap connectors; and a shaft operatively connected to said switch, said shaft having a pointer attached to it, at least a part of said pointer being outboard of said enclosure, said pointer having a first indicator part and a second indicator part associated with it, one of said first and said second indicator parts being adapted to indicate a position on said first scale and the other of said first and said second indicator parts being adapted to indicate a position on said second scale as said pointer is rotated through 360*.
 2. The apparatus of claim 1 wherein said shaft is spring biased outwardly of said enclosure.
 3. The apparatus of claim 2 wherein said switch includes a hub having an axial opening in it, said axial opening including a first axial length having a first diameter and a second axial length having a second diameter.
 4. In a welding apparatus having an enclosure, a transformer mounted in said enclosure including a core of magnetic material and a winding composed of wire turns mounted on said core, said winding defining a primary side and a secondary side for said transformer, the improvement comprising a switch assembly, said switch assembly including a body part and a shaft, said shaft being rotatably mounted to said body part at a first end and having a pointer mounted on a second end of it, said switch body having a plurality of terminals, individual ones of said terminals having preselected individual ones of said wire turns physically attached to it, said enclosure having at least a first scale and a second scale concentrically arranged on it, each of said scales extending over an arc of less than 180*, said pointer having a first indicator part and a second indicator part associated with it, one of said first and said second indicator parts adapted to indicate a position on said first scale and the other of said first and said second indicator parts adapted to indicate a position on said second scale sequentially as said shaft is rotated through 360*.
 5. The apparatus of claim 4 wherein said shaft is spring biased outwardly of said enclosure.
 6. The improvement of claim 5 wherein said switch body is circular in plan and includes a centrally located hub having an axial opening therethrough, said shaft extending through said axial opening, said axial opening having a first axial length of a first diameter, and a second axial length of a second diameter, said hub receiving said shaft along the second end of said shaft, said first and said second diameters permitting concentric movement of said shaft.
 7. The improvement of claim 6 wherein said switch body has a plurality of grooves formed in it and a plurality of tap connectors mounted to said body along said grooves, said tap connectors defining said plurality of switch positions, said movable contact being selectively engagable with individual ones of said tap connectors.
 8. The improvement of claim 7 wherein said tap connectors are L-shaped in side elevation and are mounted to said switch body along one leg of said L-shape and extending outboardly upwardly of said switch body along a second leg of said L-shape.
 9. The improvement of claim 8 wherein each of said L-shaped tap connectors has a tine formed in said second leg.
 10. The improvement of claim 9 wherein said secondary winding includes a first coil part disposed about said core, said coil part being formed by a plurality of wire turns wound in layers about said core, the outermost layer of said wire turns beiNg formed in loops at preselected intervals along said layer, individual ones of said wire loops being electrically connected to said tap connectors along said tine of said second leg.
 11. In a welding apparatus having an enclosure, a transformer mounted in said enclosure including a core of magnetic material and a winding composed of wire turns mounted on said core, said winding defining a primary side and a secondary side for said transformer, the improvement comprising a switch assembly, said switch assembly including a body part and a shaft, said shaft having a first end and a second end, said shaft being rotatably mounted to said body part at its first end and having a pointer mounted along its second end, said switch body having a plurality of terminals, individual ones of said terminals having preselected ones of said wire turns electrically attached to it, said enclosure having at least a first scale and a second scale concentrically arranged on it, each of said scales extending over an arc of less than 180*, said pointer having a first indicator part and a second indicator part associated with it, one of said first and said second indicator parts adapted to indicate a position on said first scale and the other of said first and said second indicator parts adapted to indicate a position on said second scale sequentially as said shaft is rotated through 360*.
 12. The improvement of claim 11 wherein said secondary side has said wire turns wound in layers, preselected ones of said wire turns of said secondary side being looped in their manufacture, said wire loops being formed from the outermost layer, with respect to said core, of said secondary side of said winding.
 13. The improvement of claim 12 wherein said terminals comprise L-shaped connectors, one of the legs of said L-shape having a tine formed in it, the wire loops of said secondary side being placed over said tine to physically attach said secondary side to said switch assembly.
 14. The improvement of claim 12 wherein said terminals comprise L-shaped connectors, said wire loops of said secondary side being soldered to one leg of said L-shape to physically attach said second winding to said switch assembly.
 15. In a welding apparatus having an enclosure, said enclosure having at least one opening in it, a transformer mounted in said enclosure including a core of magnetic material and a winding formed from a plurality of wire turns mounted on said core, said winding defining a primary side and a secondary side for said transformer, the improvement comprising a switch assembly, said switch assembly including a body part and a shaft, said body part including a hub having an axial opening through it, said axial opening having a first axial length with a first diameter, and a second axial length with a second diameter, said shaft having a first end and a second end, said hub receiving said shaft along the first end of said shaft, the arrangement of said first and said second diameters permitting axial and radial movement of said shaft, said radial movement of said shaft permitting the second end of said shaft to be aligned with the opening in said enclosure and allow free rotation of said shaft, said shaft having a pointer mounted along the second end of it, said switch body having a plurality of terminals, individual ones of said terminals having preselected individual ones of the wire turns defining said secondary side of said transformer electrically connected to it.
 16. The apparatus of claim 15 wherein said enclosure has at least a first scale and a second scale concentrically arranged about said opening, each of said scales extending over an arc of less than 180*, said pointer having a first indicator part and a second indicator part associated with it, one of said first and said second indicator parts being adapted to indicate a position on said first scale and the other of said first and said second indicator parts being adapted to indicate a position on saiD second scale as said pointer is rotated through 360*.
 17. The apparatus of claim 16 wherein said shaft is spring biased outwardly of said enclosure.
 18. The apparatus of claim 16 wherein said secondary side of said transformer includes at least a secondary winding coil having a plurality of turns arranged in layers about said core, the wire turns of said secondary coil being looped in their manufacture, said wire loops being formed from the outermost layer, with respect to said core, of said wire turns. 